NULL pointer dereference in Xen
CVE-2020-29571
An issue was discovered in Xen through 4.14.x. A bounds check common to most operation time functions specific to FIFO event channels depends on the CPU observing consistent state. While the producer side uses appropriately ordered writes, the consumer side isn't protected against re-ordered reads, and may hence end up de-referencing a NULL pointer. Malicious or buggy guest kernels can mount a Denial of Service (DoS) attack affecting the entire system. Only Arm systems may be vulnerable. Whether a system is vulnerable depends on the specific CPU. x86 systems are not vulnerable.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.2 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.004 (30.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 30th percentile — 30.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: +0.000
Affected products
- Xen
- Debian Linux — versions 10.0
- Fedoraproject Fedora — versions 32, 33
Weakness classification (CWE)
References
- xenbits.xenproject.org/xsa/advisory-359.html (Patch, Vendor Advisory)
- www.debian.org/security/2020/dsa-4812 (vendor-advisory, Third Party Advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- security.gentoo.org/glsa/202107-30 (vendor-advisory, Third Party Advisory)
Frequently asked questions
- What is CVE-2020-29571?
- CVE-2020-29571 is a medium-severity vulnerability in Xen, classified under NULL Pointer Dereference. CVSS score: 6.2/10. Published 2020-12-15.
- How severe is CVE-2020-29571?
- Medium severity. CVSS v3 base score is 6.2 out of 10.